GOCE is a slender, winged ion-driven satellite launched to glide through the upper atmosphere for nearly two years measuring Earth's gravity field with unprecedented precision. GOCE data will also provide a new understanding of tectonic activity that could lead to better forecasts of earthquakes and volcanoes. Scientists expect changes in Earth's interior to show up in the satellite's gravity measurements. GOCE, which stands for the Gravity field and steady-state Ocean Circulation Explorer, is the first of six ESA Earth Explorer satellites built to focus on aspects of processes affecting the planet's climate.